The superior colliculus of the cat receives visual input from the retina and the visual cortex and has access to motor systems of the brainstem controlling head and eye position. The object of the proposed research is to develop detailed information about the influence of corticotectal and retinotectal inputs on collicular neurons which project to regions of the nervous system involved in orienting and visually guided behavior. This information is necessary to an understanding of how the colliculus participates in the transformation of a sensory code to a motor code, and how the visual cortex influences such a sensory-motor transformation. The research project is designed to study the visual responses of cells projecting from the superior colliculus to different parts of the nervous system. The analysis will also focus on the separate and combined roles of the corticotectal and retinotectal inputs in determining the behavior of these tectal output cells. Finally, the possible functions of these cells in determining the behavior of oculomotor neurons will be investigated.